Application of Radar Rainfall Estimates Using the Local Gauge Correction Method to Hydrologic Model

Abstract

The Radar-AWS Rainrate (RAR) calculation system operated by Korea Meteorological Administration has several limitations in estimating the rainfall amounts accurately, though the RAR calculation system estimates rainrate from real-time estimation of the Z-R relation using the reflectivity from weather radar and observed rainrate from Automatic Weather Station (AWS). This study applied the Local Gauge Correction (LGC) method which enables correcting the rainfall events occurred locally using the RAR calculation system and verified the accuracy of the LGC results. As a result, in the case analysis of the summer season (from June 2012 to August 2012), RMSE and correlation coefficient of the RAR calculation system are 6.39 and 0.87 and RMSE and correlation coefficient are 2.45 and 0.85, respectively, in the winter season (from December 2012 to February 2013). Therefore, the RAR calculation system has the accuracy of rainrate estimation. In this study, after the LGC method is applied to the RAR system, the accuracy of the RAR is improved in both summer (from 8.68 to 8.01 in RMSE) and winter seasons (from 2.58 to 2.00). The LGC method has also improved about 3 % than the Gauge to Radar (G/R) ratio. Furthermore, the corrected rainfall using the LGC method was inputted to the HEC-HMS to examine the accuracy of flood simulation. According to the results, the accuracy of flood results with the LGC method was improved 11.57% (in RMSE), 2.11% (in correlation coefficient), and 14.47% (Nash-Sutcliffe Efficiency) on average, along with the accuracy of hydrograph with the LGC method. Therefore, after the application of the LGC method, the RAR calculation system has sufficient capability to simulate the accurate rainrate while the LGC method can correct the amounts of rainrate from the RAR calculation system. It is advised that the corrected rainfall with the LGC method be utilized in hydrology field to produce more accurate hydrologic variables.

Comparative Application of Rain Gauge, Ground- and Space-Borne Radar Precipitation Products for Flood Simulations in a Dam Watershed in South Korea

“…The LGC approach applies weights that account for discrepancies between measurements from Automated Weather Stations (AWSs) and values derived from radar, allowing for the correction of ground radar-based gridded precipitation [48]. Detailed methodology regarding this technique can be found in Lee et al [49], and Figure 3 illustrates the comprehensive process of the RAR algorithm, incorporating the Local Gauge Correction method [47,50].…”

Comparison of Quantitative Precipitation Estimation Algorithms using Dual Polarization Radar Measurements in Korea

“…넓은 지역에 대해 고해상도의 시공간 분해능을 갖는 레 이더 추정 강수는 산악지역에 대한 돌발홍수 예측이나 홍수 예보의 정확도 향상에 큰 가능성을 지닌 것으로 평가되고 있 으며 (Bae et al, 2012), 그동안 많은 관련 연구가 진행되어 왔 다 (Collier et al, 1986;Seo, 1998;Bringi et al, 2001;Borga, 2002;Thorndahl et al, 2014). 특히 국내에서는 단일 편파 레이더의 오차 및 면적평균환산의 오차, 지상 강우자료 의 합성 및 보정 방법, 레이더 반사도의 수직분포에 대한 보 정 등 레이더 추정 강수의 정확도를 평가하고 향상시키기 위 한 연구 (Bae et al, 2012;Kim et al, , 2009Kim et al, , 2010Kim et al, , 2011Kim and Yoo, 2014;Lee et al, 2014;Yoo et al, 2008Yoo et al, , 2009Yoo et al, , 2011aYoo and Yoon, 2010;Yoon et al, 2014b)와 레이더 추정 강우를 활용한 수문학적 홍수 모의 및 산사태 등 재해 예측 기법을 중심으로 많은 연구 (Ham and Hwang, 2014;Noh et al, 2013Noh et al, , 2014Park and Hur, 2009;Yoon et al, 2014a)가 진행되었다. 한편, 최근 수평편파만을 사용하는 기존의 단일 편파 레이 더에 비해 수직 편파를 추가로 사용하여 여러 수문 기상 변수 를 관측하는 이중 편파 기술의 도입에 의해 레이더의 강수 추 정 성능이 향상되고 있다 (Jeon et al, 2012;Lee, 2013;Lim et al, 2013b (Jeon et al, 2012;Lee, 2013).…”